1. Field of the Invention
The present invention relates generally to loading mechanisms and recording and reproduction apparatuses, and more particularly to a loading mechanism, provided in a recording and reproduction apparatus for performing recording on or reproduction from an information recording medium such as an optical disk, for moving a tray on which the information recording medium is placed between a position for performing recording on and reproduction from the information recording medium and a position for removing the information recording medium, and to a recording and reproduction apparatus including the loading mechanism.
2. Description of the Related Art
This type of conventional loading mechanism employs configurations disclosed in Japanese Laid-Open Patent Application No. 2002-208206 and Japanese Patent No. 2925919 in order to stably hold the tray and guide the movement of the tray.
A description is given, with reference to FIGS. 1 through 3C, of an optical disk drive unit having a conventional loading mechanism. FIG. 1 is a perspective view of the optical disk drive unit. The optical disk drive unit includes a unit main body 1 in which a tray 3, an optical pickup (not graphically represented), and a loading mechanism (not graphically represented) are provided. An optical disk 2 as an information recording medium, such as a CD-R, is placed on the tray 3. The optical pickup optically records information on and reproduces information from the optical disk 2 housed inside the unit main body 1. The loading mechanism moves the tray 3 between a housing position at which the optical pickup optically records information on or reproduces information from the optical disk 2 (or a position at which the tray 3 is housed inside the unit main body 1) and an ejecting position at which the optical disk 2 is removed from the tray 3 (or a position at which the tray 3 is ejected from the unit main body 1 to the outside as shown in FIG. 1).
The unit main body 1 includes a box-like cover 4 and a front panel 5 provided to close the front side of the cover 4. A rectangular opening 5a is formed substantially in the center of the front panel 5. An eject button 6 for ejecting or retracting the tray 3 is provided in the vicinity of the opening 5a. By operating the eject button 6, the tray 3 can be moved back and forth in the A′ and A directions between the inside and the outside of the unit main body 1 through the opening 5a of the front panel 5.
The tray 3 is formed of plastic, for instance. A disk placement part 3a on which the optical disk 2 is placed is formed on the upper surface of the tray 3. The disk placement part 3a includes a substantially circular stepped recess. Further, a through opening 3b is formed in the tray 3 along the Z-axis.
FIG. 2 is a cross-sectional view of the optical disk drive unit of FIG. 1, taken in the Y-Z plane, showing the configurational relationship between the tray 3 and a holding member provided in the unit main body 1. Referring to FIG. 2, a guide part 8 is formed on each Y-directional end of the tray 3 so as to extend along the X-axis. Each guide part 8 has a groove part 8a formed at the bottom thereof so as to extend along the X-axis. On the other hand, the mechanisms and components forming the drive unit are provided to a frame 7 provided inside the unit main body 1 as the holding member. A plurality of bosses 9 are provided on each Y-directional end of the frame 7 in a straight line substantially parallel to the X-axis so as to project along the Z-axis (as projections each having an end thereof facing in the Z direction in FIG. 2). FIG. 2 shows only a pair of bosses 9.
The groove parts 8a and the bosses 9 are fitted together (or engaged) with play being provided therebetween so that the tray 3 is movable (slidable) in the A and A′ directions of FIG. 1 along the bosses 9. Further, a plurality of tray holding parts 10 are formed to protrude from the frame 7 so as to press the upper part of each Y-directional end of the tray 3 toward the bosses 9. As a result, the groove parts 8a and the bosses 9 are held in the fitted state so that the groove parts 8a are prevented from disengaging from the bosses 9.
The rapid spread of information equipment in recent years has increased the number of opportunities for users who are not necessarily experienced in handling information apparatuses to use them. Further, there is also a continuing rapid increase in the number of opportunities to use information apparatuses at home, so that there are more opportunities for children to use drive units of the above-described configuration. If the drive unit is used under these circumstances, a wrong use of the drive unit or unintentional contact with the drive unit by the user may cause a great external force to be exerted on the tray 3 in the above-described second position. It is desirable that the drive unit continue to operate normally even in such a case.
In the above-described drive unit, each groove part 8a of the tray 3 and the bosses 9 of the frame 7 are fitted together (or engaged) with slight clearance (play) provided therebetween as shown in FIG. 3A so that the tray 3 and the frame 7 are held to be movable relative to each other. When an external force is applied to the tray 3, the bosses 9 and the peripheral portion of each groove part 8a deform elastically as shown in FIG. 3B. When a great impact is applied to the tray 3, in the worst case, the tray 3 may disengage from the guiding bosses 9 of the frame 7 as shown in FIG. 3C so that it may not be possible to return the tray 3 and the frame 7 to the fitted state.
In order to prevent such disengagement of the tray 3 from the bosses 9 of the guide parts 8, the groove parts 8a and the bosses 9 may be fitted together in a longer and deeper region. In order to provide such a structure, however, it is necessary to increase the height dimensions of the groove parts 8a and the bosses 9 in the loading mechanism of the tray 3. This increase in the size of the loading mechanism not only leads to an increase in the size of the entire drive unit, but also causes another problem such as a limitation of types of electronic components mountable in the vicinity of the loading mechanism.